<template>
  <!-- <div>自定义组件com1-{{ a }}
    <button @click="$emit('update:a', a+1)">+1</button>
  </div> -->
  <div>自定义组件com1-{{ value }}
    <button @click="$emit('input', value+1)">+1</button>
  </div>
</template>
<script>
export default {
  props: {
    // a: { type: Number, required: true }
    // b: { type: Number, required: true }
    value: { type: Number, required: true }
  }
}
</script>
